// 第一个类：Person
class Person {
    // 属性
    private String name;
    private int age;
    private String gender;
    private String occupation;
    private String address;

    // 构造方法
    public Person(String name, int age, String gender, String occupation, String address) {
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.occupation = occupation;
        this.address = address;
    }

    public Person(String name, int age, String gender) {
        this.name = name;
        this.age = age;
        this.gender = gender;
        this.occupation = "Unknown";
        this.address = "Unknown";
    }

    // 方法
    public void introduce() {
        System.out.println("My name is " + name + ".");
        System.out.println("I am " + age + " years old.");
        System.out.println("I am a " + gender + ".");
        System.out.println("I am currently working as a " + occupation + ".");
        System.out.println("I live at " + address + ".");
    }

    public void work() {
        System.out.println("I am working as a " + occupation + ".");
        System.out.println("I enjoy my work.");
    }

    public void celebrateBirthday() {
        age++;
        System.out.println("It's my birthday! Now I am " + age + " years old.");
    }
}